Biology Department, University of Dayton, 45469-2320, Dayton, OH, USA.
Planta. 1990 Nov;182(4):486-91. doi: 10.1007/BF02341022.
To locate functionally the primary site of auxin action in growing cells, the pool of auxin relevant to induction of growth in maize (Zea mays L.) coleoptile sections was determined. A positive correlation was consistently noted between growth and intracellular levels of indole-3-acetic acid (IAA), i.e. growth appears to be relatively independent of the external level of IAA. N-1-Naphthylphthalamic acid (NPA), a potent inhibitor of auxin transport, was used to enhance accumulation of IAA in coleoptile cells. From the use of NPA, it is shown that: 1) increasing the accumulation of IAA in cells, while the external concentration is held constant, resulted in a concomitant increase in growth, and 2) blocking the exit of IAA from cells with NPA sustained an IAA-induced growth response in the absence of externally applied IAA. Furthermore, the absence of any alterations in auxin binding to microsomal fractions by NPA indicates that the action of NPA in causing enhancement of auxin-induced growth is based upon its inhibition of efflux of IAA from the cells.
为了确定生长素在生长细胞中主要作用部位的功能位置，测定了与诱导玉米（Zea mays L.）胚芽鞘切段生长相关的生长素库。生长素的浓度与生长之间始终存在正相关关系，也就是说，生长似乎相对独立于生长素的外部水平。N-1-萘基邻氨甲酰苯甲酸（NPA）是一种有效的生长素运输抑制剂，用于增强胚芽鞘细胞中生长素的积累。从 NPA 的使用中可以看出：1）在保持外部浓度不变的情况下，增加细胞内生长素的积累会导致生长的相应增加，2）用 NPA 阻止生长素从细胞中输出，可以在没有外部施加生长素的情况下维持生长素诱导的生长反应。此外，NPA 对质膜部分生长素结合没有任何改变，表明 NPA 增强生长素诱导生长的作用是基于它抑制生长素从细胞中流出。
